An overview of mountain meteorological effects relevant to fire behaviour and bushfire risk

2009 ◽  
Vol 18 (7) ◽  
pp. 737 ◽  
Author(s):  
Jason J. Sharples
Keyword(s):  
Management Practices ◽  
Complex Dynamics ◽  
Fire Regimes ◽  
Emergent Properties ◽  
Fire Weather ◽  
Fire Behaviour ◽  
Rugged Terrain ◽  
Wide Range ◽  
In Fire ◽  
Meteorological Effects

Many of the processes that can occur in mountainous landscapes have the potential to significantly affect fire behaviour and bushfire risk in general. These processes can lead to otherwise unexpected fire behaviour and escalation in fire size and severity that could endanger firefighting crews and compromise suppression activities. Interaction of upper winds with rugged terrain can often result in highly variable and turbulent wind patterns and variations in temperature and humidity that can affect fire regimes in the long and short term. More generally, the effect of rugged terrain on atmospheric flows can give rise to complex dynamics and emergent properties that are discontinuous in nature. Hence, the ‘fire weather continuum’ that is often assumed in fire management practices is of reduced validity in mountainous or hilly landscapes. This paper presents an overview of the main elements of mountain meteorology relevant to fire weather and discusses the potential roles they may play in bushfire behaviour, development and risk. As such, the paper is intended to promote understanding, across the wide range of professions concerned with bushfire, of how mountain meteorological effects might contribute to fire potential and fire behaviour.

Fire regime shift linked to increased forest density in a piñon–juniper savanna landscape

2014 ◽  
Vol 23 (2) ◽  
pp. 234 ◽  
Author(s):  
Ellis Q. Margolis
Keyword(s):  
Regime Shift ◽  
Fire History ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Climatic Conditions ◽  
Tree Density ◽  
High Severity ◽  
Wide Range ◽  
In Fire

Piñon–juniper (PJ) fire regimes are generally characterised as infrequent high-severity. However, PJ ecosystems vary across a large geographic and bio-climatic range and little is known about one of the principal PJ functional types, PJ savannas. It is logical that (1) grass in PJ savannas could support frequent, low-severity fire and (2) exclusion of frequent fire could explain increased tree density in PJ savannas. To assess these hypotheses I used dendroecological methods to reconstruct fire history and forest structure in a PJ-dominated savanna. Evidence of high-severity fire was not observed. From 112 fire-scarred trees I reconstructed 87 fire years (1547–1899). Mean fire interval was 7.8 years for fires recorded at ≥2 sites. Tree establishment was negatively correlated with fire frequency (r=–0.74) and peak PJ establishment was synchronous with dry (unfavourable) conditions and a regime shift (decline) in fire frequency in the late 1800s. The collapse of the grass-fuelled, frequent, surface fire regime in this PJ savanna was likely the primary driver of current high tree density (mean=881treesha–1) that is >600% of the historical estimate. Variability in bio-climatic conditions likely drive variability in fire regimes across the wide range of PJ ecosystems.

scholarly journals Testing Vegetation Flammability: The Problem of Extremely Low Ignition Frequency and Overall Flammability Score

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Zorica Kauf ◽  
Andreas Fangmeier ◽  
Roman Rosavec ◽  
Željko Španjol
Keyword(s):  
Leaf Litter ◽  
Management Practices ◽  
Fire Regime ◽  
Fire Regimes ◽  
Testing Methods ◽  
Testing Conditions ◽  
Similar Materials ◽  
Measured Information ◽  
In Fire ◽  
Extreme Fire

In the recent decades changes in fire regimes led to higher vulnerability of fire prone ecosystems, with vegetation being the only component influencing fire regime which can be managed in order to reduce probability of extreme fire events. For these management practices to be effective reliable information on the vegetation flammability is being crucial. Epiradiator based testing methods are one of the methods commonly used to investigate vegetation flammability and decrease in ignition frequency is always interpreted as a decrease in flammability. Furthermore, gathered information is often combined into a single flammability score. Here we present results of leaf litter testing which, together with previously conducted research on similar materials, show that material with very low ignition frequency under certain testing conditions can be extremely flammable if testing conditions are slightly changed. Additionally, our results indicate that combining measured information into one single flammability score, even though sometimes useful, is not always meaningful and should be performed with caution.

Potentially limited detectability of short-term changes in boreal fire regimes: a simulation study

2010 ◽  
Vol 19 (8) ◽  
pp. 1140 ◽  
Author(s):  
Juha M. Metsaranta
Keyword(s):  
Sustainable Forest Management ◽  
Null Model ◽  
Fire Regimes ◽  
Late 20Th Century ◽  
Fire Cycle ◽  
Early 21St Century ◽  
Boreal Plains ◽  
Area Burned ◽  
Wide Range ◽  
In Fire

Climate change is expected to increase area burned in the boreal plains ecozone of Canada in the early 21st century (2001–50). I examined the influence of inter-annual variability in area burned and short observed time series on the probability of detecting if an increase has occurred, using a null model of present and future fire regimes. A wide range of fire cycles are consistent with annual area burned in the late 20th century (1959–99). Fire cycles estimated from the reciprocal of the average annual burn fraction over a 50-year period are not very precise, and overestimate the fire cycle if years with large annual area burned have not recently occurred. Under the default assumptions, the probability of detecting a doubling of annual area burned during 2001–50 is 73% if it occurred instantaneously, but only 31% if it occurred gradually. Imprecise estimates and uncertainty in the ability to detect changes in fire cycles poses challenges for implementing aspects of sustainable forest management. Alternate empirical or model-based statistics, such as return periods for annual areas burned of a given magnitude, may be useful for inferring frequencies and magnitudes of large fire years that have not yet been observed.

The Importance of Vegetation Build Up for Burnt Area Seasonality

2020 ◽  
Author(s):  
Alexander Kuhn-Regnier ◽  
Apostolos Voulgarakis ◽  
Sandy Harrison ◽  
Colin Prentice
Keyword(s):  
Cloud Cover ◽  
Management Practices ◽  
Fire Regimes ◽  
Exact Nature ◽  
Contributing Factors ◽  
Burnt Area ◽  
Vegetation Productivity ◽  
Fire Models ◽  
In Fire ◽  
The Relationship

<p>Vegetation build up is a major controlling factor for wildfires globally. The exact nature of the dependency of wildfire activity on past vegetation productivity is still under debate, however. Given the potential future rise in conditions conducive to extremely damaging fires in many regions of the world, controlling factors like this need to be investigated urgently to better understand and manage especially extreme wildfire events.<br>To improve our understanding of wildfires and the advice given to policy makers, a comprehensive understanding of all contributing factors is required. Changes to land management can be controversial and thus concrete evidence is required to assess and modify longstanding management practices and regulations if needed.<br>We therefore used global satellite datasets extending from 2005 to 2011 to assess the relationship between burnt area and various biophysical variables. Vegetation proxy data included vegetation optical depth and the fraction of absorbed photosynthetically activate radiation. Different regions and time periods were analysed separately to isolate regional and temporal effects respectively. The relationship between pre-season vegetation productivity and burnt area was modelled as a regionally and temporally varying weighted sum of past monthly productivity proxies.<br>As expected, significant differences in fire regimes were found across biomes, signified for example by significant shifts in the seasonality of burnt area. Understanding these shifts in the seasonality of both burnt area and the accompanying temporal dependence on past vegetation growth is key to reproducing observed wildfire regimes in fire models. As these relationships were found to vary both temporally and regionally, judicious inclusion of biophysical variables in fire models coupled with algorithms able to capture these relationships is necessary. <br>However, remotely sensed observations were of different quality in different areas due to inhomogeneous cloud cover patterns, making assessments for much-affected regions like South America and South East Asia especially difficult. Likewise, the found correlation between decreasing cloud cover and increasing burnt area biased our results. Due also to the short time span of the data available in this investigation, these factors warrant further investigation to more fully quantify the temporal and regional relationships at work.</p>

Less fuel for the fire: malleefowl (Leipoa ocellata) nesting activity affects fuel loads and fire behaviour

2016 ◽  
Vol 43 (8) ◽  
pp. 640 ◽  
Author(s):  
Amy Smith ◽  
Sarah C. Avitabile ◽  
Steven W. J. Leonard
Keyword(s):  
Fire Regimes ◽  
Fire Intensity ◽  
Fire Behaviour ◽  
Minimum Diameter ◽  
Behaviour Modelling ◽  
Fuel Loads ◽  
Eastern Australia ◽  
In Fire ◽  
Nesting Activity ◽  
Mound Sites

Context Fire is an important driver of species distributions globally. At the same time, biota also influence fire regimes. Animal activities that modify fuel characteristics may influence fire regimes and hence ecosystem function. However, apart from herbivory, animal effects on fuels and fire behaviour have rarely been studied. Aims We examined the effect of nest building by malleefowl (Leipoa ocellata) on litter fuel loads and fire behaviour in the fire-prone, semiarid mallee ecosystem of south-eastern Australia. Malleefowl nests consist of mounds constructed by raking large amounts of leaf litter from the surrounding area. Mound-building activity is likely to affect fuel loads and potentially affect fire behaviour in this environment. Methods Litter cover and mass were compared between paired mound and non-mound sites. Fire behaviour modelling was used to determine whether differences in fuel load were likely to translate into differences in fire behaviour. Additionally, in an area recently burnt by wildfire, the minimum diameter of burnt stems was compared between mound and non-mound sites to determine the effects of malleefowl activity on fire intensity. Key results Malleefowl nesting activity reduced litter fuel loads around mounds. Fire behaviour modelling and post-fire minimum stem diameter measurements showed this led to reduced fire intensity around mounds, even under extreme fire weather conditions. Conclusions The likelihood and intensity of fire is reduced around active malleefowl mounds. Malleefowl nesting contributes to more heterogeneous burn patterns in mallee vegetation. This in turn may contribute to the formation of fire refuges. Implications Few studies have examined the effects of animal activities on fire. This study demonstrates that non-trophic interactions of fauna with fuels may influence fire regimes. Species that reduce or disrupt the continuity or connectivity of fuels could have similar effects to malleefowl in fire-prone regions. Further examination of the interactions of animals and fire regimes will contribute to a better understanding and conservation management of fire-prone ecosystems.

Simulating effects of climate change and ecological restoration on fire behaviour in a south-western USA ponderosa pine forest

2012 ◽  
Vol 21 (6) ◽  
pp. 731 ◽  
Author(s):  
Kristen A. Honig ◽  
Peter Z. Fulé
Keyword(s):  
Climate Change ◽  
Ecological Restoration ◽  
Ponderosa Pine ◽  
Fire Weather ◽  
Fire Behaviour ◽  
Western Usa ◽  
Ponderosa Pine Forests ◽  
Full Treatment ◽  
Tree Removal ◽  
In Fire

Global climate change has the potential to affect future wildfire activity, particularly in south-western USA ponderosa pine forests that have been substantially altered by land-use practices and aggressive fire suppression. Using two regional general circulation models for the A1B greenhouse gas emission scenario, Australia’s CSIRO:MK3 and Germany’s MPIM:ECHAM5, we predicted fire behaviour under the 80th, 90th and 97th percentiles of future fire-weather conditions at a study site on the Kaibab National Forest, Arizona. We then altered the fuel structure by simulating alternative ecological restoration treatments: a full treatment (FULL), a full treatment with a 40.6-cm-diameter restriction on tree removal (16″ CAP) and a full treatment with a 25.4-cm-diameter restriction on tree removal (10″ CAP). Model results show that differences in fire weather (temperature and fuel moistures) expected by the end of the 21st century were not influential enough to alter fire behaviour significantly, but treatments did significantly reduce severe burning. Alteration of fuel structure through the 16″ CAP and FULL ecological restoration treatments caused significant declines in fire behaviour and crown fire activity under all climate scenarios. The 10″ CAP substantially reduced treatment effectiveness.

Impression management and legitimacy strategies: The BP case

2013 ◽  
pp. 35-64 ◽  
Author(s):  
Giovanna Michelon
Keyword(s):  
Impression Management ◽  
Management Practices ◽  
Legitimacy Theory ◽  
British Petroleum ◽  
Wide Range ◽  
Management Techniques ◽  
Disclosure Tone ◽  
The Empirical Analysis ◽  
A Company ◽  
Texas City

The aim of this paper is to study if and how impression management varies during different phases of the legitimation process, in particular during the legitimacy building and legitimacy repairing phases (Suchman, 1995). We aim at understanding whether and how the disclosure tone adopted by a company in the two different moments is diverse and thus functional to the intrinsic objective of the each phase. The empirical analysis focuses on the case of British Petroleum Plc. We investigated the impression management practices undertaken by the company both during the preparation of the rebranding operation, i.e. a situation in which the company is trying to build legitimacy; and during the happenings of two legitimacy crises, like the explosion of the refinery in Texas City and the oil spill in the Gulf of Mexico. The evidence appears in line with the theoretical prediction of legitimacy theory. Results show that while the company tends to privilege image enhancement techniques during the legitimacy-building phase, it uses more obfuscation techniques when managing a legitimacy-repairing process. Moreover, the analysis suggests that the company makes more extensive use of impression management techniques in the disclosures addressed to shareholders, investors and other market operators than in the disclosures addressed to the wide range of other stakeholders.

scholarly journals Fitness of Herbicide-Resistant Weeds: Current Knowledge and Implications for Management

Plants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 469 ◽  
Author(s):  
Vila-Aiub
Keyword(s):  
Life History ◽  
Herbicide Resistance ◽  
Management Practices ◽  
Current Knowledge ◽  
Resistance Management ◽  
Fitness Cost ◽  
Plant Fitness ◽  
Resistance Mutations ◽  
Fitness Costs ◽  
Wide Range

Herbicide resistance is the ultimate evidence of the extraordinary capacity of weeds to evolve under stressful conditions. Despite the extraordinary plant fitness advantage endowed by herbicide resistance mutations in agroecosystems under herbicide selection, resistance mutations are predicted to exhibit an adaptation cost (i.e., fitness cost), relative to the susceptible wild-type, in herbicide untreated conditions. Fitness costs associated with herbicide resistance mutations are not universal and their expression depends on the particular mutation, genetic background, dominance of the fitness cost, and environmental conditions. The detrimental effects of herbicide resistance mutations on plant fitness may arise as a direct impact on fitness-related traits and/or coevolution with changes in other life history traits that ultimately may lead to fitness costs under particular ecological conditions. This brings the idea that a “lower adaptive value” of herbicide resistance mutations represents an opportunity for the design of resistance management practices that could minimize the evolution of herbicide resistance. It is evident that the challenge for weed management practices aiming to control, minimize, or even reverse the frequency of resistance mutations in the agricultural landscape is to “create” those agroecological conditions that could expose, exploit, and exacerbate those life history and/or fitness traits affecting the evolution of herbicide resistance mutations. Ideally, resistance management should implement a wide range of cultural practices leading to environmentally mediated fitness costs associated with herbicide resistance mutations.

scholarly journals Environmental Drivers and Age Trends in Site Productivity for Oak in Southern Poland

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 209
Author(s):  
Luiza Tymińska-Czabańska ◽  
Jarosław Socha ◽  
Marek Maj ◽  
Dominika Cywicka ◽  
Xo Viet Hoang Duong
Keyword(s):  
Nitrogen Deposition ◽  
Management Practices ◽  
Additive Model ◽  
Climatic Conditions ◽  
Environmental Indicators ◽  
Environmental Drivers ◽  
Site Productivity ◽  
Site Factors ◽  
Wide Range ◽  
Si Model

Site productivity provides critical information for forest management practices and is a fundamental measure in forestry. It is determined using site index (SI) models, which are developed using two primary groups of methods, namely, phytocentric (plant-based) or geocentric (earth-based). Geocentric methods allow for direct site growth modelling, in which the SI is predicted using multiple environmental indicators. However, changes in non-static site factors—particularly nitrogen deposition and rising CO2 concentration—lead to an increase in site productivity, which may be visible as an age trend in the SI. In this study, we developed a geocentric SI model for oak. For the development of the SI model, we used data from 150 sample plots, representing a wide range of local topographic and site conditions. A generalized additive model was used to model site productivity. We found that the oak SI depended predominantly on physicochemical soil properties—mainly nitrogen, carbon, sand, and clay content. Additionally, the oak SI value was found to be slightly shaped by the topography, especially by altitude above sea level, and topographic position. We also detected a significant relationship between the SI and the age of oak stands, indicating the long-term increasing site productivity for oak, most likely caused by nitrogen deposition and changes in climatic conditions. The developed geocentric site productivity model for oak explained 77.2% of the SI variation.

scholarly journals A Cross-sectional Survey of the North American Skull Base Society: Current Practice Patterns of Vestibular Schwannoma Evaluation and Management in North America

2017 ◽  
Vol 79 (03) ◽  
pp. 289-296 ◽  
Author(s):  
Jamie Van Gompel ◽  
R. Wiet ◽  
Nicole Tombers ◽  
Anand Devaiah ◽  
Devyani Lal ◽  
...  
Keyword(s):  
North America ◽  
Skull Base ◽  
Vestibular Schwannoma ◽  
North American ◽  
Management Practices ◽  
Current Practice ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Number Of Patients ◽  
Wide Range

Background Very few studies have examined vestibular schwannoma (VS) management trends across centers and between providers. The objective of this study is to examine current practice trends, variance in treatment philosophies, and nuanced or controversial aspects of VS care across North America. Methods This is a cross-sectional survey of North American Skull Base Society (NASBS) members who report regular involvement in VS care. Results A total of 57 completed surveys were returned. Most respondents claimed to have over 20 years of experience and the majority reported working in an academic practice with an affiliated otolaryngology and/or neurosurgery residency program. Sixty-three percent of respondents claimed to evaluate VS patients in clinic with both an otolaryngologist and neurosurgeon involved. Eighty-six percent of respondents claimed to operate on VS with both an otolaryngologist and neurosurgeon involved, while only 18% of neurosurgeons and 9% of otolaryngologists performed surgery alone. There was a wide range in the number of cases evaluated at each center annually. Similarly, there was wide variation in the number of patients treated with microsurgery and radiation at each center. Additional details regarding management preferences for microsurgery, stereotactic radiosurgery, stereotactic radiotherapy, and conservative observation are presented. Conclusion VS management practices vary between providers and centers. Overall, most centers employ a multidisciplinary approach to management with collaboration between otolaryngology and neurosurgery. Overall, survey responses concur with previous studies suggesting a shift toward conservatism in management.

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